Juan Martín del Potro squeezed into the quarter-finals of the Delray Beach Open yesterday, defeating Bosnian Damir Dzumhur – the first time the two have met on the circuit – 7-6 (5), 4-6, 6-3 in what turned out to be a frustrating encounter.

Delpo had been looking to build on his positive but patchy performance earlier in the week; however, last night’s match proved less than straightforward. His first set was blighted by double faults, five to be exact, before eventually winning the tie-break.

The second set saw more of the same, with del Potro going 3-1 ahead, before letting his no.72 ranked opponent back into the game. Dzumhur took hold and broke Delpo’s serve in the ninth game and had the chance to win it with a match point, but went down 6-4 in the end.

The Argentine continued to struggle in the third, making his frustrations loud and clear, shouting “How the fuck am I going to win playing like this!?” after yet another double fault and a missed chance to break in the fourth game.

But, he returned in the sixth with a better sense of rhythm to his game and from there saw the game out with relative ease, following 2h25m of play.

Next up, Delpo will face the man who knocked him out of the tournament at the semi-final stage last year, no.35 ranked Sam Querrey, for what will surely be his toughest test of the week so far.